An advantage of views is
Answer: A
Correct answer: All of the above
All three are genuine advantages. A view can omit columns a user should not see, present computed columns that exist nowhere in the base tables, and stand in for a complicated query so that users need write only a simple one against it.
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Which among the following field type is used to store photograph of employees?
Answer: C
Correct answer: OLE
An OLE Object field stores an embedded or linked file - a photograph, a document, a spreadsheet. There is no Picture or Photo field type; Memo holds text only.
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The metadata is created by the
Answer: C
Correct answer: DDL interpreter
Metadata - the description of tables, columns and constraints - is produced when a schema is defined, so it is the DDL processor that writes it into the data dictionary. DML compilers and query interpreters read that metadata but do not create it.
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The fact that information in the data warehouse changes far less often and may be regarded as non-real-time with periodic updating; This implies that data warehouses are _______
Answer: B
Correct answer: Non - Volatile
A data warehouse is loaded periodically and then read; existing data is not overwritten by day-to-day transactions. That is what non-volatile means here, and it is what allows historical comparisons that an operational database cannot support.
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Which of the following is not a characteristic of a relational database model?
Answer: B
Correct answer: Tree like structure
A relational database is a set of independent tables with no structural links between them; relationships are expressed by matching values, not by pointers. The tree is the hierarchical model's structure.
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______ keyword is used to find the number of values in a column.
Answer: C
Correct answer: COUNT
COUNT returns the number of values; SUM adds them. The distinction matters because \( \text{COUNT}(column) \) counts only the non-null values, while \( \text{COUNT}(*) \) counts rows.
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It is an abstraction through which relationships are treated as higher level entities
Answer: C
Correct answer: Aggregation.
Aggregation lets a relationship be treated as an entity, so that another relationship can be defined on it. Generalisation and specialisation relate entity sets to each other rather than promoting a relationship.
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____ First proposed the process of normalization.
Answer: C
Correct answer: Edgar F. Codd
E. F. Codd, who invented the relational model at IBM in 1970, also introduced normalisation and defined the first three normal forms.
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Dependency preservation is not guaranteed in
Answer: A
Correct answer: BCNF
Every relation can be decomposed into 3NF while keeping all its functional dependencies, but a decomposition into BCNF may not be able to preserve them all. That is the one guarantee BCNF gives up in exchange for removing every remaining redundancy.
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In SQL the statement select * from R, S is equivalent to
Answer: B
Correct answer: Select * from R cross join S.
Listing two tables in the FROM clause with a comma and no join condition produces every combination of their rows - the Cartesian product, which is what CROSS JOIN means. A natural join would match on the common columns, which is a different result.
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